Automatic telephone-exchange system.



n. E. GLEMBNT. AUTOMATIG TELEPHONE EXCHANGE SYSTEM. APPLICATION IILED BBPT. 18, 1905'. I 1,107,138. Patented Aug. 11, 1914.

s sun's-sum 1.

E. E. CLEMENT. AUTOMATIC TELEPHONE nxcamon sYs'rEu. APPLICATION IILBD 81221. 10, 1005.

1,107,138. Patented Aug.11,1914;-

: inns-ans! i Z 5 agent I E. -E. CLEMENT. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION IILED SEPT.18, 1906.

1,1Q7J38. Patented Aug.11,1914.

3 SHEETS-SHEET 3.

3s wantoz nnirnn STATES l P T T ornron.

nnwaann. CLEMENT, or WASHINGTON,

DISTRICT or COLUMBIA, ASSIGNOR, BY

w MESNE ASSIGNMENTS, TO FREDERICK 0., STEVEN S, OF ATTICA, YORK.

To all-whom it may concern Be it known that I, EDWARD E. CLEMENT, a citizen of the United States, residing at Washington, in the District of Columbia, have inventeda certain new and useful Improvement in Automatic 'Telephone Exchange Systems, of which the following is a specification, reference being had therein to the accompanying drawing.

My invention relates to automatic telephone exchange systems, and has for its object the improvement thereof in the matters of efliciency stalling and operating.

I attain my object in a manner which will be hereafter pointed out.

Heretofore, various more or less complicated contrivances have been required at the subscribers station to produce impulses over one line-wire or the other and ground, or both at once and ground, and, to regulate the durationand arrangement of these im-. subscribers sender to its simplest possible form, a simple the circuit being all that pulses or both. I reduce the make and break of I use, all current changes moreover con the same length, andall apparatus acting. I difi'erentiate between Ibelieve I am the first successfully to operateautomatic systems in the mannerdescribed by merely making and breaking the metallic or other circuit, and I shall'claim the same accordingly.

H'eretofore it has been customary to provide each line at the central ofiice with a switching device by which it could be connected through associated devices with other lines. In large exchanges this means that assuming the number of subscribers lines is 100 per cent, under ordinary conditions there would be at least 120 per cent. of switches, and according to the best practice there would be 100 contacts in each switch. I reduce the total number of switches below the number of lines, providing means whereby the various switches may serve each a number of different lines. lliloreover, I provide for means to distribute the calls more uniformly than is now possible.

Specification of Letters Patent. Application filed September 18, 1905. Serial No. 279,031.

and cost, the'latter both in in a well-known form stituting the controlling impulses, being of positive the switching impulses and those which Imay denomimarginal AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

Patented Aug. 11, 1914.

According to my present invention, each line has a signal relay at the central office by which when it calls multiple answering contacts in a number of' what I shall call primary selector switches have their potential raised, and thereupon the first primary selector to reach one of said contacts in'its constant revolution, stops upon it and'there by connects the line too. chain of automatic switches which may be of any required arrangement or pattern. The operation of my primary selector switch is identical with that of an operator. The latter sticks a plug in answering a call, thereby energizing the cut-off relay, and connecting the line with whatever apparatus is in the cord-circuit. Myprimary selector lands a contact or sticks a plug, preferably the latter, thereby ener izing the cut-01f relay, and connect ingthe line with the switching apparatus.

very important feature of iny invention is this, that-it can he Y pplied as a connecting link between manual lines and automatic exchange apparatus of any type. I have illustrated 'it'used in connection with a of two-wire multiple common battery subscribers line, and thrsocalled Strowger' automatic exchange 'appa- 'ratus, employed in many large plants with which telephone engineers are familiar; but after reading the following detailed description, it will become obvious that its use is not limited to any particular type of line or exchange. It may be employed in existing automatic exchanges in order to convert them into common battery installations and to simplify. the subscribers line and sub-station apparatus, as wellas. to in crease the capacity oftheexchange apparatus; or it may be employed in connection with existing manual systems to replace the central oflice equipment withautomatic switches or to increase the capacity.

The invention is illustrated in the accompanying drawings, in Which- V Figure 1 is a: diagram showing sub= 'scribers line and a primary selector by which it can be picked up when' calling. Fig. 2- is a complementary figure'tol'Fig; 1, showing first and second selectors of the Strowger type, with a connector therefor. Fig. 3 is a diagram showing the same circuit as Fig. 1, but a modified form of 'primary selector, which I prefer.

The general scheme may'be stated-in a winding of a relay and to rest .upon the actual line-terminals battery current both to the line and to the long as the receiver is ed the hook at the I so that he may goahead and transmit the number wanted. I

- magnet so that the signal ever, and

' he is connected, or rather that his call has few words: Taking Figs. 1 and 2 together, I I will assume subscriber A to be calling, and the primary selector P to be the one which picks him up. He takes his telephone ofif the hook, whereupon his line-relay at. central is energized and connects battery to the contacts, ;0, in the primary selector bands. Each primary selector is normally driven at a constant rate of speed by means of a shaft and clutch controlled. by a magnet. A wiper contact forms a terminal for the which controls the magnet, so that when the switch has brought its test wiper on the terminal contact. corresponding .to and made alive by the line 'calling, it stops. A pair of independent wipers are connected to move with the test wiper,

when the test wiper rests upon the associated testterminal. Hence when the switch stops the line is put through onto the central oflice connective circuit, and at the same time the latter is closed so as to supply cut-off relay thereof, whereby the line-relay is removed. The control of the clutch magnet circuit of the primary selector switch'is then transferred to a relay on the connective circuit fed with current from the line. As

sub-station, this rela will continue to hold the switch on the line-contact.

The foregoing action takes but a small interval of time, usually but a fraction of a second, and I provide means whereby the subscriber may know that he' is connected prefer to do this by reversing thebattery connections normally on 'being in series with the line and those in the switch circuit, providing a polarized indicator at the subscribers station which is normally concealed, but is displayed as soon as the battery is reversed in making connection with the line. If a sender is employed in which all the numbers can be set up and retained until released, I polarize the controlling or a part thereof may come in as soon as connection is eii'ected to theline. Such a device is shown for instance in the patent granted to E. A. Faller, 757 ,031, April 12, 190 1. By polarizing the magnet and arranging ,the contact devices in a manner well understood by those familiar with the art, it might be used in the present system. Its use is optional, howfor the sake of simplicity as well as because the sending device in itself forms no part of thepresent invention, I do not 1iillustrate it, preferring to show a simple Having received the signal showing that been answered at central, the subscriber proceeds to send the number wanted, thereby atom.

the switches at central to connect his line t rough to the line wanted.

The essential features of my invention are found in Figs. 1 and 3. Referring first to Fig. 1, the substation A is provided with theusual transmitter, receiver and switchhook, which when up cuts in the talking set and when down cuts in the ringer Q. addition, I provide the low-wound signal magnet Q, controlling the target which operatin nounces the answer to the call, and the key K for breaking and making the circuit, both the talking set. The line-wires 12 pass to the contacts or armatures n, n of the cut-ofi relay N, and thence normal} to the wires 5 and 6 leading respective y to the line-relay M and to ground. The relay is connected on the other side by wire 7 to the battery, B, which preferably supplies current for all purposes. The local circuit 8 controlled by a contact connected by wire 10 tothe bank te'st contacts p in a set of the primary selectors P. The swltch 9 represents one of the arms of a gang switch by which a given set of lines may be shifted during the busy hour to wiresll, 12 and 13, leading to bank contacts in other groups of primary selee-tors. This is'a purely optional provision, but shows how flexible the system is. When the cut-off relay N is energized it disconnects the armature hr; n, from the line relay and ground and connects them to the wires 3 and 1 leading to the talking contacts p in the primary selector banks. The pair of talking contacts p, associated with each line, bear a fixed relation ta the test contacts 7) in each switch.

The selector switch has a spindle, 2), carrying insulated contact arms or wipers, p, 5 adapted to be rotated around the spindle continuously, and to sweep over the bank contacts 72, p of the various dines The spindle is kept rotating by means of a clutch connection with a shaft P, shown as driven by a'belt, P The clutch is shown at P having a member, p,"fixed on the shaft, P and an interlocking member, 2, splined on 'the spindle, p. This is controlled by the forked end of an armature lever, 0, controlled by an electromagnot, 0, associated with the selector. A fixed stop,

the line-relay M ter- ,minates in a switch 9 normally restingupon p, is supported on the frame of the switch in the path of the movable member or collar of the clutch, so that when the magnet pulls down the lever 0 against the tension of the spring, 0, the clutch member, 2 will not only be disengaged from the shaft member, 7), but will engage the stop, and the further rotation of the spindle is thereby prevented.

The wiper, p, is carried on a .ring upon which rests a contact brush, 19 connected by a wire 14 to the relay S and ground.

Wiper, 7), 1s carried by a similar ring upon which rests a contact brush, p, forming the terminal of a wire, 15, corresponding to the tip conductor of an ordinary cord-circult. lViper p is carried by a similar rin upon which rests a brush, 79 forming the terminal of a wire 16, which corresponds to the sleeve conductor of an ordinary cordcircuit. These two wires corresponding to the tip and sleeve conductors of a cord-circuit, constitute the primary portion of the talking circuit, and terminate in condensers, C, from the other side of which wires 21 and .22 pass to the first selector switch of an ordinary automatic set, constituting in fact the so-called vertical and rotary wires, respectively, of said switch. The wire 15 is normally interrupted at contacts (F, d of a solenoid relay D with which it is connected through the branches 17-18. Wire 16 is similarly normally interrupted at contacts 0Z (Z of the same relay, with. which it is connected through the branch wires 19' and 20. The core, d, of this relay is normally down or retracted, maintaining these contacts open, and the winding ofthe relay is connected on one side by the wire 23 to ground, and on the other side by the wire 24 to the wires 25 and 26, the former passing to a front contact of the test relay S and the latter to a front contact of the supervisory relay S. Armature s of relay S is connected to the battery wire 7 by means of the of the relay.

branch 27; and the armature s S is connected to the battery wire 7 through wire 28, leading to the front contact of relay j goes to battery by way of the wires 29 and 30. When the.

S whose armature 8 switch is connected with a line the relay S retains current as long as the connection v lasts, controlling the battery supply to the i switch magnets at such time. wire 34 is tapped oil from the ceiving current as long as the of the solenoid relay D.

The branch wire 28, re- 5 relay S is energized, and conveying it to the spring'd lVhile the relay is f denergized, all its springs are separated ex- 1 cept d 03 contact, connecting and d", which are maintained inf the battery wire 3a with the wires 35 and 36, leading from springs (Z7 and (Z to the vertical and rotary wires 21 and 22. The solenoid relay D takes its.

current through wire 32, and

momentarily closes together sprlngs (Z, d

; armature, shown at 1, which in pulling up or letting go. These springs are connected, re- 5 spectively, to the wire 37, leading from wire 22, and the wire 38, leading from the wire 24, which latter takes current from the wire 28 when the relay S is energized.

The magnetrO, ing and stopping connected on one other through the of the solenoid D.

of the primary selector, is side to ground and on the wire 39'to the spring d which controls the start- Having thus described the essential features of the apparatus wherein my invention particularly resides, I will now pass to a set of automatic selector switches with which it is intended to work conveniently, translating mere makes and breaks in the metallic circuit of the line into whatever impulses, over whatever branches, are required. These switches are shown in Fig. 2, being designated respectivefy by the letters, F, and F. They are of the types shown in the Keith and Erickson Patent 815,321, granted March 13 1906. The wires 21 and 22 which are bro (en at the righthand side of Fi 1, commence again at the left-hand side 0% Fig. 2 and pass to switch arms 47 and 48, which normally rest upon contacts forming terminals of the wires 40 and 42, leading respectively to the relay magnets V and R, which are called the vertical and rotary relays of the first selector switch F. Impulses coming overthe wire 21 when the switch is normal affect the relay V, passing through its windings to ground, While impulses going over the wire22 afl'ect the relay R, passing through its windings to ground.

The switch F comprises a rotary spindle f, carrying insulated contact wipers w, 10 which are adapted to sweep over a set of contacts w and 10 constituting the terminals of trunk conductors 210 and 220 passing to second selector switches. The spindle also carries an insulated test and release wiper w", which sweeps over a set of contacts 10 the talking circuits w and 'w but forming the terminals of test and release circuits 60 for the second selector switches.

The vertical relay V controls a magnet V, called the vertical magnet, which is provided with a ratchet mechanism to step the spindle f up to the desired row of contacts, w, e0 10 these contacts being arranged in horizontal rows of ten eacl. The rotary relay R controls whatis called net R, which is fitted with a ratchet mechanism by which it can turn the spindle f, one step at a time, making its wipers rest upon one set of contacts after another in the respective rows selected. The magnet It is automatic in its operation, that is to say it carries an insulating wedge on its acts to make and break its own circuit as it vibrates. The armature also carries a projecting lug or stud, r which in operation impinges against the armature t of the magnet T", whose function will appear in the statement of operation.

U is the release magnet, an armature lever, which upon being attracted will lift the retaining pawls oil" the ratchets of the spindle f, ter to be turned back to zero and dropped to its normal position by a suitable spring.

T is the test and release relay, connected equipped with corresponding to the contacts of z its the rotory magpermitting the latwire 50 tothewiper w.

that moment active.

The switch-arms 46, 47, L8 and 49 mounted as a unit and moved together, step at a time, being all set back into position shown in the drawing when magnet U- restores the switch to its zero or and being thence released of an esoapement inactive position, step by step by means carried by the armature t of the relay T The second selector-switch F, and its cuits, are identical are marked V the switch-M11 49 and on spindle f 49 is on .the middle contact, the relay T back through wire the moment of testing is energized so as to render the relay T at in s all essential particu lars with the first selector and its circuits. The vertical and rotary relays in this switch and R the vertical and row of line-contacts; and this magnet is connected to battery by the wire 74. With the switch-arm 67 in the second position, the wire 78 is put into connection, with the wire 79 and thence with the rotary magnet .Rfiefitted toturn the spindle f step by stfi "1;, not after the fashion of the selector relays, R and R", but only as energized for each .step' separately. Thus, the spindle may be turned around to a particular contact in the selected row. With the switch-arm 67 in its third position the wire 78 is connected to the wire 81 and so to the ringing relay Z, which controls the contacts .2, z, 2 z", a and 2 these contacts being included in the two sides 65 and 66 of the talking circuit wires, terminating on the switch-arms. 68 and 69, open during selection, but at the last stage, when the subscriber wanted is actually connected, closed to the wires 71 are one I the the cirrotarymagnets are marked V and E the and 7 2 leading to the talking circuit wipers private or controlling relay is T, the test 1w". and w". When the magnet Z is enerand release relay is T,

net is U w 'w and w while the trunk terminals the connector groups tor, each with a naughtadded. Thus, trunk-wires are arms are 4:60 470, 480, and 490, etc.

'It will be observed that the vertical and rotary relays and magnets are cut off last step of the come, this is not so. This switch is 1. type shownin the 40"ent-815,176, granted March 13, 1906.

Vertical and rotary relays V and R ,both' intended to work the switch spindle 1' during connection.

stepby step, and serve to afford control over all series, working. through Wires and the relaysT, T,

the switches in etc. From switches, ,the wire 61 comes condenser. the relay-V side. From 62 a branch 64 extends to relay. R, which. :isgrounded likewise on otherv side, manent. v 1

The vertical relay V controls a local cuit 78, passing tromthe spring '0, to a pair of contacts on: the relayT to the switcharm 67. Remembering that the arms 67, 69 and 70 all move together as controlled by. the escapementpf the magnet T,

normal position of into connect-ion with the 35 the vertical magnet V which raises and the release mag- The switch wipers are marked are marked 'w, 'w and v v The circuits bear the same numbers as I "their corresponding wlres in the first selec- 130' 210 and 220, the side switchside switch-arms heretofore described, leaving a clean talking circuit. In the connector switch F to which we, new

Keith and Erickson Pat- The' the back release both these branches being perarm 67 puts the .wire 78 wire 80, thence to gized it Works its contacts just as an ordinary manual ringing key does, breaking the conductors and 0'6, and connecting the forward ends to he generator G v U is the release and test magnet, X

are bridged battery or retardation coils in the battery supply circuit to the called line. The functions of these and other parts will appear further from the statement of operation.

It'will now be possible to comprehend, the operation the the

of my invention as embodied in the apparatus illustrated in Figs. 1 and 2.

-j I have "not shown the substantion and line of the subscriber to be called, but these are suppose 'to be the same as the substation A and, -1ne12. We will assume the subscriberA' to be calling. He takes his receiver from'the hook, closing the line-circuit through his talking set as follows: P, 7, th M, 5, 11,-, 1, K, switch-hook, talking set, Q, i 2, n, 6 and ground back to battery. The

relay M becoming energized pulls up its an mature and closes a circuit from battery to the contact 12 in the primary selector banks, 'as follows 5,13, 7, m, 8, 9, 10, 72. The contacts p thus having their potential raised, when anyone of them is touched by the wipe! 72 of a primary selector switch in its revolution, a circuit is closed from the battery to the relay S, through 7, S, 9, f6, 12, 71 'p and 14:. The relay S thereupon pulls up its armature s and closes the circuit of solenoid D: B, 7, 27, s, 25, 24, D, 23 and ground'back to battery. The solenoid thereupon instantly pulls up-its core, the arrangement being such that the core will pull up very quickly, but relax and drop down very slowly. This may be secured in a considerable degree by simply making the core fit rather closely in its channel. The current in the windings 1 find brings it up the 1 are its

the 1 e cirthe,

the

step by step to select the desired "then very sharply, while the comparatively small force exerted by gravity pulls it down against atmospheric resistance very slowly. To increase the difference I use a check valve in the top of the, spool of the solenoid, ar-

ranged to open outwardly. When the core rises, this permits the confined air to escape quickly, but when the core falls the air is admitted very slowly and the core therefore is equally sluggish in falling. As soon as the core (Z is pulled up it opens the springs a", (Z and d", which are normally closed together, and closes together the springs (Z a and d, al on the one side, with (3*, d and (P, d on the other side. The effect of this is to complete the continuity of the wires 15 and 16 from the contacts p and p to the relays S and S so that current from the main battery B Will at once flow out over the line-circuit as follows: B, 7, 30, S 20, (Z (i 19, 16, p W, p, 4, N, ground and back to battery; then as soon as this causes the energization of relay N, in parallel therewith from 4 to n, 2, Q, talking set, switch-hook key K 1 n 3 4 15, 18, d d relay S, groiind bzi cli to battery. The relay S is energized by the same current as and hence simultaneously with the cut-elf relay N, putting current on the wire 28; the relay S is energized as soon as the cut-E relay N acts, pulling up its armature andkeeping the batteryon the wire 24 through the branch 26, this being necessary because the relay 8 is out off and ceases to :2: supply current through the wire This occiJu-s in the following manner: The actua tion of the cut-off relay N disconnects the wires 5 and 6 from the line-wires 1 and 2, whereupon the line-relay M of course loses current, the circuit 7, 8, 9 and 10 is opened, and hence relay S is cut off.

In drawing up its armature and closing the springs d and (Z together, 'the'solenoid D completes the operating circuit of the stop magnet O, as follows: B, 7, 30, 29, 8 34, ii", (Z 39, O and ground back to battery. This magnet O pulls down its armature and the lever 0, disengages the upper part of the clutch member 32 from the shaft plate 39 and brings the lower face of the clutch member against the stop p. l have shown both faces of the clutch member serrated to insure a good grip. The stop, p has an edge which takes into the teeth. The spindle p is thereupon stopped, and the wipers 72 79* and p remain on the contacts p and 7), connecting the calling line 1, 2, 3 and 4 with the conductors 15, 16, and maintaining the connection as long as the line-circuit is closed at the substation, which means as long as the relay S is energized. It will be understood that while the operations of the several relays have been recounted seriatc'm, they really occur so nearly simultaneously that the wipers, 39 p and 39 have not time to pass off the line contacts 2?, calling before the magnet O is the switch is stopped.

It will be observed upon tracing the fore going circuits that when the solenoid D pulls up and puts battery through the conductors 15 and 16 to line, this battery is reversed in direction from that normally on the line. Hence the polarized magnet Q at the substation will reverse its armature upon the position shown, raising the target and indicating to the subscriber that his call is answered and switches placed at his command. He then proceeds to manipulate the key K so as to connect himself with the line wanted.

I preferably provide a suflicient number of primary selectors for each group of lines so that each line may have at least ten multiple contacts of each of the sets 39 and 79. These contacts are either identical in every switch as to their angular position, (in which case the wipers 79 p and 1 must be displaced one step in each succeeding switch) or the contacts of the same line may be displaced and set in each succeeding switch, and the wipers in all the switches of a set may then have the same angular position with relation to the shaft 32 The solenoid D has no part in the action of selecting the line and stopping the switch. Its function is in transmitting the impulses to the automatic switches. Assume that subscriber A desires to converse with subscriber No. 2468. He first taps the key K twice, each time breaking the circuit and quickly making it again. He then permits a short interval to elapse. The first short break causes the relay S in Fig. 1 to let go its armature, whereby for a brief instant current is transmitted over the following circuit: B, 7, 30, 29, 28, 3 31, 32, D, 23,'and ground. At the same time current is sent over a second branch from the wire 3-1 by way of 33, d", (l and 35 to the wire 21. This is the vertical side of line, and the pulse of current proceeds to the first selector switch in Fig. 2, which will be referred to presently. That portion of the current. which reaches solenoid D causes it to pull up quickly, closing the springs cl, (Z together in passing, but it should he noted that while this closes the circuit 3'7, 38, it does not produce any effect because battery is disconnected from the wire 26 and hence from the wire 24, because at the instant the solenoid pulls up the armature s of the relay S is back. -It is true that this also takes current off of the solenoid D, but the break is very short, and while either solenoid will pull up on a momentary impulse, neither of them will fall back far enough to perform any work except on a long change in current. Hence the solenoid D is unaffected by the short number impulses coming over the line. Both solenoids p, of the line energized and now have their cores attracted, and so long as the subscriber is sending short breaks, thereby oscillating the armature a back and forth, just so long will both solenoids hold up. Each closure of the armature s on its back contact sends a pulse of current to the wire 21 by the path already traced, so that in calling 2468 two breaks being made, two pulses of current will be sent, and then as the subscriber leaves his line circuit closed, the relay S will continue to hold up, and the solenoid D, being deprived of current for a considerable eriod, will let its core retract far enough tc close the springs 03, (Z and send. a single pulse or" current to the wire 22 by the following path: B, 7, 30, 29, 8 28, 8 26, 24, 38, 01'', d, 37, and 22. The wire 22 is the socalled rotary wire of the first selector switch ,in Fig. 2. Thus two short breaks produced in the metallic circuit have been translated into two current impulses on the vertical side 21, and one impulse following the group, on the rotary side 22. In a similar manner the next number, 4, is transmitted by making four short breaks at the key K, which are translated into four impulses on the vertical side 21, followed by one impulse on the rotary side 22. Each succeeding group of short breaks is translated in the same way, all that the subscriber has to do to send the number I have mentioned being to tap the key twice, then four times, then six times, and finally eight times, leaving a reasonable interval between the groups. Here the peculiar features of my invention end., So far as the present application. is concerned, any desired form and arrangement of switches and circuitsimay be adopted, and it will be found that my solenoids and relay scheme of Fig. 1 will enable any standard switches to be worked merely by the subscriber making and breaking the metallic circuit. I emphasize this because it is exceedingly important for two reasons. In the first place it is undesirable and is now considered bad practice to have any grounds on the lines if they can be avoided; and in the second place I am enabled to apply my present invention to existing common battery systems having metallic circuits by merely supplying a separate box or casing with the circuit breaker K of any desired type, and the signal device Q. To connect this for operation requires merely that its binding posts shall be interpolated in the talking circuit.

I have shown how by tapping his key the subscriber sends successive groups of imulses over the wire 21, and a single impulse at the end of each group over wire 22. This is all it is necessary to assume or to remember in order to understand Fig. 2. The first two impulses come over the wire 21 and cause the relay V to pull up twice, each time closing the following circuit: battery B, 7,

memes 55, 5'1 V, 56, contacts of magnet T, 59, v. g, 60, and back to battery. This causes the magnet V to step up the spindle f two steps, so as to bring the contact wipers 'w, w and 'w" opposite the second rows of contacts. trunks 210, 220 and test wires 60, leading to 10 second selector switches of the order of 2000. Following the group of two impulses over wire 21, comes the single impulse from wire 22. This energizes rotary magnet R, which pulls up and closes the following circuit: battery B, 7, 55, T 7" 6' and back to battery. The magnet T t ereupon pulls up, breaking the circuit 56-59 oi: the vertical magnet V, and making the first movement of the escapement so that upon the retraction of the armature t, the side switch arms i6, 47, 4:8 and 49 are permitted to move one step, whereupon the following circult is immediately closed for the rotary magnet R: battery B, 7, 55, 57, It, 58, 46, 43 and ground back to battery. The rotary magnet R thereupon pulls up, its stud, 7", breaks the circuit and it lets go, the stud closes the circuit and it pulls up again, and so on with the following results: Each time the armature of the rotary magnet pulls up, it steps around the spindle f one step, and causes each wiper to pass from one contact to the next, making contact with the succeeding one, however, before it leaves the preceding one: At each movement of the armature of the rotary relay, the armature t of the relay T is kicked up by the stud 9, but released when the wipers come on a fresh contact. That is to say, on the forward stroke the armature t is forced to take the first step toward moving the escapement to release the side switch-arms for their last step. Now as the wiper w passes over the successive contacts w of the different trunks all leading to second selectors numbered 2000, it is hunting for an idle one, and the idea is to have the side switch move a third step when an idle trunk is found, Each contact that is busy has a ground on it, as will presently appear. Hence, if in its first movement the wiper w finds such a grounded contact, it will at once close the following circuit: Battery, 7, 55, T", 52, 49, T, 50, w", 10 and ground back to battery. As stated, on the first part of the stroke the armature t is mechanically held up. Current flowing in the circuit I have traced holds it up in the second. part of the stroke of the rotary arn'iature, so that after the armature t is once kicked up, it stays up, held alternately by the stud 1 and by itsown magnet T until an idle or underground contact w is reached. lVhen this happens the armature 1; falls back, and its escapement permits the four switches 46, 47, 48 and 49 to take their last step. Switch 46 cuts off the rotary magnet In these rows are the terminals of' llii \ and stops the machine instantly. 4:7 and 48 cut off the vertical and rotary relays V and R, and complete the talking circuit: 21-44, 22-45. 49 cuts off the magnet T", and closes the circuit of magnet T through wire 51 to ground, thus putting a ground on the wiper w and all the multiples c0 of the contact on which it rests, rendering the trunk busy, so that no other switch can get in. It is proper to say that the magnet T will not work on the test current through any relay T We now haveat the end of the first group of two impulses, the wires 21 and 22 extended respectively as follows: 21, 47, 424:, w, w, 210, 470, V andv ground; 22, 48, 45, 'w e0 220, 480, R and ground. In other words, the circuit has been extended into the second selector switch F and the relays V and R have been substituted for those of the first selector. \Ve now have the second group of four impulses coming over the combined wires 21 and 210, followed by a single impulse over the combined wires 22 and 220. The operation of the relays and other parts is precisely the same in this switch as it was in the first selector, the only differences being in matters of release, etc., which will be touched upon later. result of the operation of this switch is to pick out an idle connector switch F and prolong the circuits as follows 21-210-61; and 22-220-62. The relays V R of the second selector are cut off, and the relays V li are substituted therefor, their connections 63 and 64 being permanent, for these two relays are used in releasing the set of switches as well as in selecting. The subscriber now sends six impulses to relay V each of which causes the same to pull up, operating the vertical magnet V over the following circuit: battery, 7, 74, V 80, 67, 78, v, 60 and ground back to battery. The number of the wanted line is 68, so that the six impulses working in this way through magnet V step up the spindle f to the sixth row of linecontacts. *The subscriber then sends a single impulse over the wire 62 to the rotary relay R, which pulls up and closes the following circuitf battery B, 7, 75, 77, T 1", 60, and ground back to battery. The magnet T pulls up and then lets go, it being observed that there is no rotatary kicker to hold it up in this case. The side switch-arms 67, 68, 69 and 70 are therefore stepped around pron'iptly one step. Vertical magnet V is thereby out out and rotary magnet R cut in, but this magnet has no vibrator, being constructed to turn the switch spindle only one step at a time. The subscriber now sends his final number 8 over the wire 61, and the same relay V responds, each time closing the followlng circuit: battery B, 7, 74, R, 79, 67, 78, v, 60, and ground back to battery. The spindle is therefore stepped The net i around until the wipers Q08, w" and to rest upon the three contacts belonging to line 68 in that hundred. A single impulse now comes over the rotary side of line, and pulls up the relay R, which closes the following circuit, after testing to see if the line is idle: battery B, 75, magnet T 1', 60 and ground back to battery. The relay T thereupon pulls up, closin the follbwing circuit: battery B, 7 7 5, re ease magnet U 76, contacts of relay T 82, 70, (this being on its second point), w or w and to the tip side of the line being tested. Now, if the line wanted, where really testing, is already connected either through a connector switch, as shown in Fig. 2, or through a primary selector switch, as shown in Fig. 1, there will be a ground on the tip side, otherwise not. In the first case, the ground will be through the wire 71, switch-arm 68, wire 65, and magnet X. In the other case it will be through the wire 3, the wiper 7 the wire 15, and the relay S. In either case, if the line is busy the release magnet U of the testing switch will pull up releasing the same and causing it to return to zero position. In other words, the subscriber does not get on to the line wanted if it is busy.

If the line wanted isnot busy, the momentary impulse over the rotary side ceases, the relays R and T let go, and the side switches go the last step, cutting off the working magnets It and V entirely, substituting the ringing relay Z through the wire 81 and the arm 67, and completing the circuit of wires 65 and 66 through 71 and 72 to the line wanted. In order to ring the wanted subscriber, the next thing is to energize the relay Z, which is ordinarily done by simply breaking the circuit at the calling subscribers station by means of a push-button. In the present system we cannot do this because a prolonged break would deenergize the solenoid D, and would release all the switches. So I do not provide any special ringing button, but after the line wanted is selected, a succession of taps on the key K is produced by the calling subscriber, and these energize the relay Z, by energizing the relay V*. I preferably make the relay Z a solenoid like those shown in Fig. 1, so thatthe succession of short closures will hold its core up as long as they continue. The energization of this relay opens the springs z, 2, and z", and closes 2 on 2 and 2' on 2 thus connecting the ringing generator G across the wipers co w. When the called subscriber answers, he derives current for his transmitter from the main battery through the bridging coils X, X.

WV hen the subscribers have finished talking, the receivers are hung up, the metallic circuit being thus opened at the sub-stations. Referring to Fig. 1, it will be observed that this opening at substation A lets 1 Sift battery is put on gothe relay S, which cuts ofi the solenoid D, whose cored drops to its normal position shown in the drawing. The springs ,11 and (1 therefore come together, and both trunk-wires 21 and 22, by the following path: B, 7, 30, 29', 8 34, d, d and at, through wires'36' and 35. Referring to Fig. 2, these simultan'eous impulses over both trunk-wires 61 and 62 eni-ergize" both relays V and R at the same time,; closing together the springs '12" and r", and the following release clrcuitz battery, 7; 7 5', U 76, 1, of, w T 490, ground back to battery. Magnet U releases and restores the connector switch F relay T closes the following release circuit: B, U,

contacts of T, .60, w, 'w", 50, T, 49, 51, andground back to battery. Magnet U thereupon releases and restores the switch F, and relay T closes thefollowing release 1 circuit: B, 7 55, U, 54, contacts of T, 'grouncl back to battery. Magnet U thereupon restores the switch F. All the autoniatic switches are therefore restored.

the solenoid D resumed the ondition shown, in Fig." 1, the circuit of magnet O was broken at the springs d", al with the result that this magnet let go, and

the spring oapulled up the lever 0, releasing the clutch member 72 from stop p throwing it onto the shaftdisk p", whereupon the switch wipers 39 p, and p are aga n rotated. As soon as they pass off the contacts 1), p, the relays S and N are dissociated, thelr circuit through the branch 1920 of the conductor 16 having alr'eadybeenbroken by the solenoid D.

In Fig. 3 I have shown a preferred modification of the primary selector switch P, all other parts being unchanged. In this figure the shaft P is constantly revolving, and I use a revolving arm having a sole- -noid with a movable core; clutched to the shaft by the inner end of the core engaging a notch p and the outer end adapted to 'engageany one of. a succession of openings in a stop ring or jack ring 29 which is concentric-with the shaft and has its openings respectively opposite corresponding groups 5 0of line and trunk contact springs 29", 9 70 the springs 12 ,29 are preferably lntegralv throughout the circle, but cut in combs, with one pair of individual members opposite each pair of line-contacts p. 'The sole noid has two windings, S and 0 which perform the same functions as the two magnets S and O, in Fig. 1. In other words, as soon as the contact 17 corresponding tothe same part in Fig. 1, comes upona charged contact, the winding S takes current and ullsin the solenoid core p", loosing the arm from the shaft and simultaneously projecting its forward insulated end through the jack ring 29 between the springs 2 I p,

thereby pressing them out against the linecontacts 29 of the calling line, and stopping the arm. The insertion of the plug in the line-jack acts just as it would in a manual system. Relays S and N get current, and S pulls up, whereupon solenoid D gets current, and the rest of the operation is the same as that heretofore described. After the wire 10 is disconnected from battery, which is necessary because otherwise the contact p would continue to test busy to other switches, the core p and its plug are held up by the winding 0 connected for convenience through spring 22 and the solid ring contact thereof through wire 39 to the contacts of solenoid D. 30 It will. be noted in Fig. 1 that the branch wire 31 is connected through the spring (5 and its companion (Z with wire 35 to one side 21 of the talking circuit, during conversation. This puts a ground on one side 35 through the lamp 8, which in practice would not be permissible. In Fig. 3 I have shown how this is avoided by providing the wire 31 with a separate terminal point, which is left open when relay S is energized, that is durin conversation.

In the claims to follow I shall. use the ex pression a set of switches to mean a complete connective outfit from the primary selector P, of whatever type, to the connector m1 F of whatever type. In a small exchange, the primary selector and connector might be the only two switches, and they might be in one structure, while in a large exchange a set would include selectors F, F, etc., as

well as a connector.

In Fig. 3, I have shown a ratchet mechanism I for the shaft P, controlled by the line relay M through a starting wire 100, connected when the relay is energized to the commutator M. The wire 10 can be connected to the commutator and the latter direct to the wire 100, however, as I have above stated, thus dispensing with one pair of contacts for the relay.

I do not herein claim broadly automatic switches controlled by relays having different time constants or through impulses of varying electrical characteristics transmitted over the subscribers metallic line circuit (including the two sides of the line in series or other circuit normally free from ground connections) inasmuch as the same is now being claimed in my application Serial No. 291,097, filed December 9, 1905.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a telephone exchange system, subscribers lines each having means to make and break the metallic circuit, a central current supply, an automatic connective apparatus comprising a selecting and calling set of switches and a primary selector switch, answering line terminals in the latconnections for the swite ter with a switch member engaging the same and means to drive it, a relay associated:

wit-h each'line, a magnet controlled thereby and controlling the primary selector switch; when the same engages the line terminals, stopping the switch thereon, controlling magnets for the selective switches, and trans latin'g. relays placed under the line-control by the primary selector, to control the said switch magnets, substantially as described" 2. In a telephone exchange system, a plu-' rality'of subscribers metallic circuits each provided with sub-station talking and signalfireceiving apparatus and means to make and break the clrcuit in accordance with a code, and central oflice connective apparatus comprising the following instrumentalities: a line relay M anda cut-off relay for each line, a primary selector switch P and means to drive the same, line terminals 79, 1), therein, a controlling magnet therefor, a trunk circuit 15.16, 2122, and selector switchcircuits connected to said trunk with controlling magnets V, V, R, R, etc., connecteel thereto, and relays S, D, D, the first respondin to all makes and breaks in the metallic circuit, the second to breaks only, and the third to makes onl together with -magnets controlled by said relays in response to the makes and breaks in the subscribers line, substantially as described.

3 In a telephone exchange system, subscribers lines, a primary selector switch comprising a normally continuously rotating spindle carrying terminal wipers, contacts for the lines in said switch, a set of automatic selective switching apparatus a trunk line constituting a talking circuit from said primary selector switch to said automatic selective switching apparatus, and means to operate the primary selector switch to stop the rotation of said parts and to effect a connection of the contacts of a calling line with said trunk and the selective switching apparatus, substantially as described.

4. In a telephone exchange system, subscribers lines, a primary selector switch having normally the lines in said automatic switches, a trunk line from the primary selector switch to the connective switches, and means directly controlled by a calling line to cause said parts of said primary selector switch to connect the contacts of the calling line for purposes of conversation through itself with the trunk and connective switches, and thence to the line wanted, substantially as rotating parts, contacts of described.

5. In a telephone exchange system, subscribers lines, an automatic connective switch, and primary select-or switches, each primary selector adapted to be connected to ated with the primary switch, a-set of connective normally rotating the automatic connective switch, auxiliary switches arranged in percentage order and associated therewith through which a call- 1ng subscriber may connect himself with any other line, line terminals multipled into the primary selector switches, line controlled actuating means individual to each line to cause the said primary selector switches to makeconnection with the contacts of a calling line, and means intermediate the primary selector and the adjoining automatic connective switch arranged to permit the subscriber to operate the connective and auxiliary switches, substantially as described.

6. In an automatic telephone exchange system, a plurality'of subscribers lines and a primary selector switch containing answering terminals therefor, a movable member for said switch, togethier with means to drive the same, so as to connect with any line having terminals therein, a centralized source of. current supply for the lines, a controlling relay associated with each line, and a controlling magnet for the primary selector automatic selective switches associselector, multiple connecting terminals for subscribers lines in one or more of said switches, and means located intermediate the primary selector switch and the adjoining automatic selective switches and arranged to be controlled by the subscribers through the primary selector switch for actuating the other switches to continue the connection to the line wanted,- substantially as described.

7. In an automatic telephone exchange system, subscribers lines and interconnecting means therefor, comprising automatic switches in permanently connected sets each having answering and calling terminals, additional calling switches with which the calling switches of the sets may connect together with means individually associated with each subscribers line for directly controlling the answering switches, and means associated with each answering terminal and becoming operative when connected with a line to control the calling switches in sequence, substantially as described.

8. In a telephone exchange system, a central office, plurality of metallic circuit lines terminating in said office,- a common source of current supply for said lines and means associated with each line for determining the'flow of current over the two sides of the line in series, a relay normally associated with each line, a number of connective circuits at the central ofiice less than the number of lines and each provided with an automatic answering switch and one or more automatic connective switches containing line terminals, and circuit connections from the line relays to the answering terminal switches whereby the same may be directly controlled by the lines when calling to effect IIO and finally to the wantedline,

connection therewith, substantially as de l scribed.

9. In an automatic telephone system, a plurality otsubscribers lines and central office connective apparatus therefor comprising selector and connective switches in sets,- each set containing a plurality of connective switches arranged in percentage order, said connective switches containing multipled called line terminals and adapted to be sequentially actuated to establish talking circuits link by link from one switch to another a number of primary selector switchescontaining multipled calling terminals, directly controlled by the lines and adapted when actuated to connect: the same with the other selector switches, and means at each subscribersstation for varying the flow of current over the two sides of his line in series to produce grou s of impulses varying inv number according to a predetermined code, together with translating devices at the central oilice afiectecl by said code changes in the metallic circuit and acting to distribute current to the switch controlling magnets to actuate the selective switching apparatus to make a connection corres onding to said code changes, substantia 1y as described.

' 10. In a telephone exchange system, a' plurality of line circuits and link connective circuits therefor each having a primary selector switch comprising a movable spindle carrying wipers forming answering terminals of the link, means to drive and means to stop said switch, multipled answering terminals for the lines in said switch, a relay for each line adapted to initially and di rectly act upon said switch to bring it into connection with the'line when calling, a relay associated with the switch then coming into connection with the line and maintaining the switch in connection therewith as long as the line is in use, and automatic means for completing the talking circuit through the switch to the line wanted, substantially as described.

11. In an automatic telephone exchange system, line circuits, an automatic primary switch comprising a constantly rotating shaft, moving switch parts connected thcre with and adapted to be disconnected therefrom for, selecting and connecting with acalling line, an automatic connector switch,

and relays associated with said primary switch for controlling said connector switch whereby the latter may effect a connection between a calling and a called line through said selector switch.

12. In an automatic telephone exchange system, a plurality of subscribers metallic circuits without grounds, a number of central ofiice link circuits less than the number of lines, a primary or answering switch adapted to connect a calling subscribers line with an idle link circuit, a selector switch constituting an advance terminal for each link circuit, subsidiary whereby each link selector tain access to wanted lines, a plurality of local actuating circuits for the selector' switches, a primary switch trunk extending switching-means switch may ,ob-.

between the primary switch and the selector switches, and means associated with the primary switch trunk, responsive to impulses over the two sides of the subscribers line in series, and adapted when actuatedto produce changes in said local switching circuits, properl distributed to set, maintain, and finally restore the switches in proper sequence respectively at the beginning, during the continuance, and at the end of each conversation. i l

13. In a telephone exchange system, a plurality of subscribers metallic line circuits, a plurality of selective switches adapted to interconnect the lines, with a plurality of controlling relays and local circuits, and primary switches with associated relays, adapted first to connect the lines when calling to the selective switches, and second to translate metallic circuit impulses into distributed impulses for the local switch circuits. 1

14.. In an automatic telephone exchange system, a plurality of subscribers lines and a primary selector switch containing answering terminals, therefor, a movable ing terminals therein,-a centralized source of current supply for the lines, a controlling controlling magnets for the primary selector, autorelay associated with each line, and

mati-c selector switches associated with the primary selector, multiple connecting terminals for the subscribers lines in oneor each switch provided member for said switch together with means todr ve the same so as ,to'connect with any line havmore switches, and means comprising a pair of relays having different time constants of operation controlled through the primary selector switch for actuating the other switches to continue the connection to the line wanted, substantially as described.

15. In a telephone exchange system, a plurality of metallic or two-wire line circuits,

primary selector switching means and cen- H tral office connective circuits and apparatus 1 associated therewith, local circuits and auxe iliary apparatus for said connective circuits and apparatus, and means associated with the primary switching means, responsive to ourrent changes in a metallic line circuit and adapted to translate the same into properl distributed current impulses directed ,to the several central ofiice circuits and apparatus for the proper operation thereof, substantially as described. p

16. In a telephone system, telephone minating in the wipers of an automatic lines; trunks; automatic switches, each trunk ter- 7 Ill switch; the said lines heine" H1l1li;l')l@{l through a plurality of sai automatic switches and appearing as waiting contacts in said automatic switches, and each of said.

automatic switches having a wiper shaft carrying the Wipers of that switch; an auniliary conductor for each line and terminao ing in waiting contacts associated with waiting contact l rminals of the line; an

terminating in a wiper associated with the wipers of the trunk; a source of continuous power; a clutch connecting said source of continuous power and the wiper shaft of the automatic switch of the trunk; and means where by, by the engagement of the wiper of the auxiliary conductor of the trunk with the waiting contact of the auxiliary conductor of a calling line, the said clutch may be operated to dissociate said source of power from the wiper shaft of the automatic switch, suhstantially as described.

17. In a telephone exchange system, telephone lines; trunks; automatic switches; each of said automatic switches havino a wiper shaft carrying the wipers of till;

switch; an auxiliary conductor for each line and terminating in waiting contacts in said automatic switches; an auxiliary conductor; for a trunk and terminating in a wiper in the automatic switch of the trunk; a source power; a clutchconnecting the 1 of continuous said source of continuous power and wiper shaft of the automatic switch of the trunk; and means whereby, by the engagement of the wiper of the auxiliary conductor of the trunk with the waiting contactof the auxiliary conductor of a calling line, the said clutch may be operated to dissociate said source of power rroni the wiper shaft of the automatic switch, substantially as de scribed 18. In a telephone system, an automatic switch, fixed contacts and movable contacts in saidswitch, supporting and driving means for said movable contacts, a source of power for said driving means, a clutch for connect-- ing the driving means with the source of power, telephone line circuits connected to the fixed contacts in the switch, and trunk connections to the movable contacts thereof, together with selective switching means associated with said trunk for connecting the same to wanted lines, and auxiliary circuits and apparatus whereby said clutch normally connects the driving means with the source of power, but is elcctro magnetically actuated to disconnect the same when the moving contacts rest upon the fixed contacts of a calling line, substantially as described,

15). In a telephone system, a plurality'of line circuits, connecting link circuits there for, an automatic switch constituting a link terminal, having a clutch normally connect mg it with a source of power, waiting or lined term r if and scope J 1 ri gethei win circuit terminals, to-

apparatus automatic switch is automation ed from its source of power wl 'ininals of an idle linlr are cos of a calling" line, and

"ough the line i r mainthe calliantially as described, w syste i, a plurality of into mice iinlr circuits therefor, llLGilllElLiC sn h a clutch nor mally connec ".ng it with a source of power, lined waiting inals in said switch for said lines, r 1d cooperat l5; link circuit terminals, to, ry electrical cincuits and apoaratus whereby said automatic switch driven until terminals of an idle linlz: nd callingl i 'istry, is then automatically isolated from its source of power, and is 'naintained isolated by means operated through the line and link circuit thus connected, substantially as described.

21, In a telephone system, telephone lines; trunws; automatic switches: each trunk tcra, ininating 1n. the wipers or an automatic switch, the said. lines being" inultiplcd through plura ity of said {lllllOllllllLlQ switches and appearing as waiting contacts in said automatic switches, and each of said automatic switches having a wiper shaft arrying the wipers that switch; an auxili. r each line and terminating in waiting COllLftCLS as :Clfiifitl with the waiting contact tern'iinals of the line; an auxiliary conductor for a and terminating in wiper associated with the wipers of the trunk; a source of continuous power; an electromagnetic clutch connecting" d source of continuous power and the wiper shaft of the automatic switch oi the trunk; and meanswhereby, by the engagement of the i viper of the auxilii v, conductor of the trunl: with the waitn'zg contact of the auxiliary conductor of a calling line, the said. clutch may be operated to disassociate said source of from l;ll wiper shaft of the automatic switch, suhsta itially as described.

multipled contacts forming terminals of said lines; wipers movable over said multipled waiting contacts; a source of power normally mechanically connected with said wipers through a clutch; means for operating said clutch to dissociate said wipers from said source of power; and means for continuing: the condition of? dissociation of said wipers :fro n d source of power, said means being uda d to continuesuch condition dcpcndent icon the calling condition of a asso ted one cl said telephone lines, suhstantiaiy dr 23. inc telephone system, lines; waiting" forming terminals of electrical circuits and,

' said lines; wipers movable over said multipled walting contacts; a wiper shaft car rying said Wipers; a continuously driven shaft; a clutch normally connecting said continuously driven shaft and said wiper I shaft; an electromagnetic controlling means for said clutch whereby said shafts may be disassociated; and means for continuing thedisassociation of said shafts dependently upon the continuance of the calling condi-. tion of a then associated one of said telephone lines substantially as described.

24.. In a telephone system, telephone lines; waiting multipled contacts forming terminals of the speech-current circuit of said lines; wipers movable over said multipled waiting contacts; a source of power nor-: mally mechanically connected with said. wipers; a clutch for disassociating said wipers from said source of power; and. means for continuing the disassociation, of said elements dependently upon the continuance of the calling condition of the telephone line then associated with said wipers through electrical connection of said wipers with the waiting contacts of the line, substantially as described.

cally with saidsource of power and to disassociate said wipers from said source of power alternatively; and means for controlling said clutch to continue the disassocia-l tion of said wipers from said source of: power, said means for controlling being operative dependently upon the continuance of the calling condition of the telephone line then associated with said wipers through electrical connection of said wipers with waiting contacts of the line, substantially as described.

26. In a telephone system, telephone lines; trunks; automatic switches; each trunk terminating in the wipers of an automatic switch, the said lines being inultipled through a plurality of said automatic switches and appearing as waiting contacts in said automatic switches, and each of said automatic switches having a wiper shaft earrying the wipers of that switch; an auxiliary conductor for each line and terminating in waiting contacts associated with the waiting contact terminals of the line; an auxiliary conductor for a trunk and tern'iinating in a wiper associated with the 'wipers of the trunk; a source of continuous power; a clutch connecting said source of continuous power and the wiper shaft of the auton'iatic switch of the trunk; means whereby, by the engagement of the wiper of the auxiliary conductor of the trunk with the waiting contact of the auxiliary conductor of a calling line, the said clutch may be operated to disassociate said source of power from the wiper shaft of the automatic switch; and other means whereby such operation of the said clutch may be continued dependently upon the continuance of the calling condition upon the telephone line then associated with the trunk through the Wipers and contacts of the automatic switch, substantially as described.

In testimony whereof I have allixed my signature in presence of two witnesses.

EDWARD E. CLEMENT. lVitnesses:

E. EDMONSTON, J12, James H. MARK.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

